Underpinning required?

[Alex3012]

Hi everyone!

 

My partner and I are in the process of renovating a bungalow, we're flipping front to back and extending the back (bedrooms we're on back and living area on the front).

 

We have completed the front of the house removing chimney breast and putting in new ensuite with the building regs required for this.

 

We're now planning the extension and to save costs I've drawn the drawings myself and will do the planning submission myself. I'm currently considering the building regs side of things. The extension is pretty simple; 5m rectangle on the back of the bungalow bringing out the exisiting roof pitch over it.

 

One of my worries is that the bungalow is adjacent to the neighbours garage (see attached rough photos) - its an odd setup I know!

 

Do you think that I will need to underpin the garage to complete the foundations for the extension? I'm drawing up the party wall agreement at the moment and building regs drawings.

 

Thanks so much in advance.

 

Alex

[markc]

Can’t see any reasons for underpinning, but you do need to look at excavation and foundations for your build to prevent the garage foundations being compromised.

i.e, if your foundations require fairly deep excavation then some form of shoring etc may be required to prevent displacement of soil from under the garage.

Edited January 10, 2022 by markc

[Alex3012]

Hi Mark, 

 

Thanks very much for your response! I was hoping that would be the case and BC have just given that advice also although not in official format. They've also advised that previous inspections of foundations have revealed clay so need to account for that in my foundation design. I'm going to do some more research to find out what exactly is required but may be a bit over me if anything other than the normal required....do you think it's worth paying for the building regs drawings (£800+ structual eng)  or continue the research...?

 

Many thanks

Alex

[markc]

Party wall agreement? yes. Struct Eng input? yes.

nothing complicated building regs wise so I wouldn’t bother have specific drawings done for that. 
pre start visit/ chat with BC and St Eng input with construction drawings should be all you need.

Detailed method statement for works on or near the party wall will go a long way.

[Carrerahill]

40 minutes ago, Alex3012 said:

Hi Mark, 

 

Thanks very much for your response! I was hoping that would be the case and BC have just given that advice also although not in official format. They've also advised that previous inspections of foundations have revealed clay so need to account for that in my foundation design. I'm going to do some more research to find out what exactly is required but may be a bit over me if anything other than the normal required....do you think it's worth paying for the building regs drawings (£800+ structual eng)  or continue the research...?

 

Many thanks

Alex

Get it professionally designed and follow the design, when the neighbours garage starts to collapse or settlement issues cause bad cracking or some other structural disturbance you will wish you had spent the £800 as it could easily cost £8000+ to fix something that goes wrong.